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When driving it feels like engine loses power

Tiny
DCOATES35
  • MEMBER
  • 1999 MERCURY COUGAR
  • 2.0L
  • 4 CYL
  • 2WD
  • MANUAL
  • 272,198 MILES
Hello Joe,

I'm sure you are tired of my car. Its been faithful to me so I put up with it. :)
Hopefully this will be the last question about something I can't figure out. So, when I'm driving my car and I'm going between 50-75 mph. I will be at a certain speed and steady for a while and my car feels likes it is losing power. It happens more often when I have my A/C on. I will be at 65 mph and the car feels like it is losing power but the speedometer never changes and then it will start working correctly. I had an electrical automotive place check it out and they said the grounds were good and they couldn't find anything wrong. I am going to have a second opinion to make sure.
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Monday, October 21st, 2019 AT 12:31 PM

37 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,709 POSTS
Welcome to 2CarPros.

Also, welcome back. As far as the issue, does it only happen when the AC is on? I ask because if the AC compressor is cycling on and off and you feel it. Please keep in mind, if the AC is off but you have the defroster on, the AC compressor will still cycle. The defroster unit uses the AC to dehumidify the air going to the windshield.

Let me know.

Joe

PS: You are welcome to come back as often as you want. I don't want you to have more problems, but enjoy hearing from you. LOL
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Tuesday, October 22nd, 2019 AT 5:09 PM
Tiny
DCOATES35
  • MEMBER
  • 45 POSTS
Thank you, it happens when the A/C is off as well. When your going fast and take your foot off the gas pedal and the speed drops. That is how it feels with my foot still on the pedal.
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Tuesday, October 22nd, 2019 AT 10:30 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,709 POSTS
Welcome back:

Interesting. Has anyone checked fuel pressure? Has the fuel filter ever been replaced? Based on the description, it sounds like it is starved for fuel. Also, it could even be related to a faulty catalytic converter. Do you ever hear any rattling under the vehicle when it's running?

Let me know.

Joe
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Wednesday, October 23rd, 2019 AT 8:44 PM
Tiny
DCOATES35
  • MEMBER
  • 45 POSTS
The last time I had the fuel filter changed was earlier this year. I get it changed with my oil, radiator flush all that good stuff. There isn't any rattling anywhere either.
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Thursday, October 24th, 2019 AT 5:25 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,709 POSTS
Welcome back:

It will become a guessing game. If I had the car, I would first pull an oxygen sensor off before the catalytic converter. That will allow more air flow. Then drive to see if it changes.

It will set an engine code, but it can be reset.

Joe
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Thursday, October 24th, 2019 AT 6:21 PM
Tiny
DCOATES35
  • MEMBER
  • 45 POSTS
I changed the one under the engine a few months ago. I am going to get the fuel filter changed and see what happens after that.
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Thursday, October 24th, 2019 AT 6:35 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,709 POSTS
Welcome back:

Let me know what you find. This is a tough one, especially because I can't drive it to feel what is happening. Anytime there is a power loss, I suspect a converter, fuel issue, and then something electrical.

I will watch for your reply.

Joe
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Thursday, October 24th, 2019 AT 8:50 PM
Tiny
DCOATES35
  • MEMBER
  • 45 POSTS
Okay, I will let you know what I find. I will check the spark plugs as well.
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Thursday, October 24th, 2019 AT 9:43 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,709 POSTS
Welcome back:

Also, make sure things like the air filter are clean and not obstructed as well as check for vacuum leaks.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

I will watch for your reply.

Joe
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Friday, October 25th, 2019 AT 4:21 PM
Tiny
DCOATES35
  • MEMBER
  • 45 POSTS
Good morning Joe,

The spark plugs were bad and I gt the fuel system flushed but it didn't solve the problem. My fuel pump is leaking, not sure if the would cause a power issue while driving. Once I'm able to get that check I will let you know what happens.
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Tuesday, November 5th, 2019 AT 4:36 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,709 POSTS
Nice to hear from you Honestly, if you have a fuel leak that can absolutely cause power loss. Anytime fuel pressure is reduced, there will be some kind of issue.

Please be careful with this problem. Any type of fuel leak can be dangerous. Let me know approximately where you feel it's leaking from so I can try to help.

Take care and be safe.

Joe
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Tuesday, November 5th, 2019 AT 10:51 AM
Tiny
DCOATES35
  • MEMBER
  • 45 POSTS
I apologize, I didn't mean to say fuel. I meant power steer pump.
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Tuesday, November 5th, 2019 AT 2:49 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,709 POSTS
Hi:

No problem. The power steering leak wouldn't cause a power loss. If you haven't already, check to confirm fuel pressure.

Joe
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Tuesday, November 5th, 2019 AT 6:02 PM
Tiny
DCOATES35
  • MEMBER
  • 45 POSTS
How do I check that? I had the fuel system flushed at Jiffy Lube.
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Wednesday, November 6th, 2019 AT 6:15 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,709 POSTS
Here is a link that shows in general how pressure is checked:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Here are the specifications for your vehicle:

FUEL PRESSURE
Key On, Engine Off (KOEO) .................... 45-60 psi
Key On, Engine Running (KOER) .................... 42-57 psi

I realize most people don't own a fuel pressure gauge. However, most parts stores will lend/rent one to you.

Let me know what you find.

Joe
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Wednesday, November 6th, 2019 AT 6:53 PM
Tiny
DCOATES35
  • MEMBER
  • 45 POSTS
I will check that out this weekend. Thank you
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Thursday, November 7th, 2019 AT 3:01 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,709 POSTS
Happy to help. Let me know what you find.

Joe
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Thursday, November 7th, 2019 AT 8:02 PM
Tiny
DCOATES35
  • MEMBER
  • 45 POSTS
Good afternoon Joe,

Apologies for the long delay. I was working a lot and couldn't get a chance to work on my car. I had the power steering pump changed and the place where I had it done said that my alternator was going bad as well. I keep forgetting to get it checked at AutoZone or O'reillys. The last time it was changed was in 2012 so it may be the cause but I know it's time to change it.
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Monday, January 13th, 2020 AT 11:46 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,709 POSTS
Great to hear from you. I hope you have a relaxing holiday.

That's interesting that they would test the alternator when replacing a power steering pump. Were there issues with the battery going low? Also, has the power issue been resolved?

Let me know.

Joe
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Monday, January 13th, 2020 AT 7:40 PM
Tiny
DCOATES35
  • MEMBER
  • 45 POSTS
It was okay, how were the holidays for you?
He didn't say he tested the alternator but I'm guessing he did since he said that. There were times where the car didn't want to start but the weather wasn't in its favor when that happened. The loss of power is still there, I am going to get it tested tomorrow for sure.
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Monday, January 13th, 2020 AT 8:02 PM

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